In recent years, IP telephone devices (IP telephones) that perform voice conversations using VoIP (Voice over Internet Protocol) are beginning to become more widespread. VoIP is a technology that achieves voice conversations on an IP network such as intranets and the Internet. With VoIP, digitally encoded voice conversations are segmented into fixed time intervals to form packets, which are sent via an IP network. There are advantages in that costs required for communications are lower than the use of a conventional telephone circuit because the line usage efficiency of an IP network is high.
Another characteristic of IP telephones is that a communication function other than voice communication can be implemented by using a protocol other than VoIP. When, for example, the device settings of an IP telephone are set, it is very laborious to input the settings of the device using the small display panel and the few operation buttons of an IP telephone. However, the settings of an IP telephone can be set from a PC browser, or, for example, the communication log of an IP telephone can be referenced from a PC browser, by using, e.g., HTTP (Hyper Text Transfer Protocol) and providing the IP telephone with a function that connects from the exterior (PC browser, for example).
In such an IP telephone system, audio is digitized, converted to IP packets, and made to flow through the IP network until reaching the destination of the telephone call. The IP packet received at the destination of the telephone call is restored to its original information, and in this manner, a telephone conversation can be carried out between the sender and the destination of the phone call.
With an IP network, the other party must be uniquely recognized by using an address such as an IP address that has been assigned to the machine. A device referred to as a gatekeeper is commonly used for this reason. A gatekeeper manages a database in which IP addresses and telephone numbers assigned to IP telephones are associated, and the IP address of a telephone as the destination of a telephone call can be specified by searching for the corresponding IP address in accordance with the telephone number specified by the IP telephone.
For example, in the IP telephone system disclosed in Patent Reference 1 (Japanese Laid-open Patent Application No. 2004-147101) described below, there is disclosed a gatekeeper device that is provided with telephone number assignment means in which a MAC address and an IP address are received from an IP telephone device before the IP telephone machine begins to operate, a telephone number set in advance on the basis of the address contained in the network address is assigned and notified to the IP telephone machine, and the telephone number, the IP address, and the MAC address are associated to perform registration and management. Using a device such as that disclosed in Patent Reference 1, the telephone number and other unique address and setting information can be automatically set for each user terminal when the power is switched on and at other times.
A presence function is a communication function other than voice communication implemented in an IP telephone, A presence function is a function for registering, managing, and transmitting the presence condition (presence state) of a user who is using a certain communication terminal (e.g., IP telephone). The user registers, in his own IP telephone, information that shows the presence state (e.g., in a meeting, out of the office, and other states), whereby the user's own presence state can be notified via the IP network to other users who are using an IP telephone.
For example, the state of counterpart users can thereby be known via the presence function before making a call from an IP telephone to an IP telephone. For this reason, time and communication expenses spent on the telephone are not wasted when a counterpart is not present, for example, because the user can confirm that the counterpart is away prior to making a call. When the counterpart user is, e.g., in a meeting, a user can decide whether to have the call transferred to the meeting room via another person, decide to wait for a while if the call is not urgent, or decide another course of action. In this manner, the presence function can be a function for assisting smooth communication between users.
An invention that utilizes a presence function is disclosed in, e.g., Patent Document 2 (Japanese Laid-open Patent Application No. 2005-18194) described below. With this invention, a communication switching system is disclosed in which a switching unit automatically transfers communications on the basis of the presence information of a user. In the system of Patent Reference 2, a presence table in which user-selectable presence states are consolidated into a list is stored in the memory of an IP telephone. Registered in the table are, e.g., present, out of the office, in a meeting, and other states of presence, and the user can select a presence from among these choices. When the user selects a presence, the presence registered in the IP telephone is notified as the presence state of the user to the switching unit, which has a presence server function.
The switching unit holds in memory a presence management table in which the presence states provided by the IP telephones are stored, and a user-classified transfer destination table in which transfer destinations corresponding to the presence of the user are stored. The switching unit thereby refers to the presence management table and checks the presence state of the user when a certain user receives a call. The switching unit acquires from the user-classified transfer destination table the transfer destination that corresponds to the presence state and performs a transfer process.
When the presence state of the user is, e.g., present, a transfer will not occur and a connection will be made to the IP telephone of the receiving destination. Also, calls will be transferred to a telephone in the meeting room when the presence state is “in a meeting,” for example. Calls will be transferred to a user's mobile telephone if the presence state is “out of the office.” In this manner, different transfer processes can be automatically performed for each presence state.
Disclosed in Patent Reference 3 (Japanese Laid-open Patent Application No. 2005-190287) described below is a gateway device and a presence display system in which presence information is synchronized among presence services that differ in SIP phone systems.
The presence display system disclosed in Patent Reference 3 is composed of a presence display system that includes mobile phones, and a SIP phone system that includes SIP phones and SIPB/W (enterprise side). The presence information of each user is stored in a presence server of the presence display system that includes mobile phones, and presence information of an SIP phone system that includes SIP phones and SIPB/W (enterprise side) is stored in the SIPG/W (enterprise side) When the presence information of the presence server has been changed, the presence server is configured to notify the SIPG/W (enterprise side) of the presence information modification via the SIPG/W (mobile communication network side); and, conversely, when the presence information of the SIP phone system has been changed, the SIPG/W (enterprise side) notifies the presence server of the presence modification via the SIPG/W (mobile communication network side).
[Patent Reference 1]: Japanese Laid-open Patent Application No. 2004-147101
[Patent Reference 2]: Japanese Laid-open Patent Application No. 2005-18194
[Patent Reference 3]: Japanese Laid-open Patent Application No. 2005-190287